Chapter 3 Part 2
Key Systems As They Relate To Human Nutrition
Cardiovascular system
- Blood flows through the heart and blood vessels from pumping of the heart
- Blood is made up of plasma, red blood cells, white blood cells, platelets and other substances
Cardiovascular systemRoutes of travel: a) Right side of heart, to lungs to
pick up oxygen and drop carbon dioxide then travels back to the heart
b) Oxygenated blood travels through arteries from the left side of the heart out to the body (capillaries) then back to the heart through veins
Cardiovascular systemExchange of nutrients, oxygen and
waste occurs in the tiny capillaries throughout the body
Cardiovascular systemPortal circulation in the
gastrointestinal tract- Capillaries in the intestines and
stomach take up nutrients from recently eaten foods
- These capillaries merge into veins that empty into the portal vein
- Portal vein leads to the liver- Liver processes the absorbed
nutrients before they enter the general circulation
Lymphatic System - Lymph flows through the lymphatic
vessels and lymph tissues- Lymph consist of plasma and white
blood cells- Lymph flows throughout the body
and eventually empties in to major veins near the heart
- Flow is driven by muscle contractions from normal body movement
Lymphatic SystemLymphatic circulation in the gastrointestinal tract:- Lymph vessels pick up the majority of products yielded from fat
absorption- These products are too large to enter the bloodstream directly
Nervous System- Controls most body functions- Basic structural and functional
unit is the neuron- Neurons respond to signals and
impulses throughout the body by releasing chemical regulators
- Transmission of the signals utilizes potassium and sodium
Nervous System- Signals between neurons use
neurotransmitters- Neurotransmitters are made
from nutrients like amino acids- Calcium is required for the
release of neurotransmitters from the neurons.
- B-12 is needed in formation of the myelin sheath which insulates most neurons
- Glucose is needed to fuel the brain
Endocrine (Hormonal) System1) Insulin: - Made in and released from the
pancreas- Helps control glucose by
allowing it's movement from the blood to muscle and adipose cells
- In liver cells, insulin stimulates conversion from glucose to glycogen for storage
Endocrine (Hormonal) System2) Epinephrine, norepinephrine,
glucagon and growth hormone all increase blood glucose
3) Thyroid hormone: - Regulates rate of metabolism
Immune System
1- Skin- Barrier surrounding the
body- Has glands that secrete
lysozyme- Deficiencies of Vit A and
zinc affect skins integrity
Immune System2- White blood cells (WBC)- Attack microorganisms by
phagocytosis, - Produce antibodies - Are the immune system cells
Digestive systemFood must be digested/ broken
down to provide us with usable nutrients
1) Mechanical Digestion: e.g. chewing
2) Chemical Digestion: e.g enzymes secretion into the GI tract to breakdown food.
Digestive systemThe Gastrointestinal tract is a tube that
extends from the mouth to the anus and is composed of 6 organs
1) MouthChewing. Tongue aids chewingTaste receptors: sweet, salty, bitter, sour
and savory (pungent) Salivary glands produce saliva1- Salivary amylase, starch digesting
enzyme2- Mucus, lubricates and makes
swallowing easier
Stomach- Secretes acid and enzymes to digest
protein- mixes and then holds food for one
to four hours- Produces chyme- Very little nutrient absorption
occurs- Chyme leaves stomach regulated by
the pyloric sphincter about 1 tsp at a time
- Produces intrinsic factor for B-12 absorption
Small intestine
- About 10 feet long and 1" in diameter
- Chyme mixes with digestive juices to digest macronutrients and prepare vitamins and minerals for absorption
- Villi are folds that create large surface area and trap food to promote nutrient absorption
Small intestineAbsorption occurs by different
processes1] Passive absorption2] Facilitated absorption3] Active absorption4] Phagocytosis and
pinocytosis.- Glucose and amino acids are
absorbed into the capillaries and to the portal vein
- Most fats go into the lymph vessels
Large intestine- 5% of unabsorbed carbohydrate,
protein, and fat reach large intestines
- Some vitamins, water, fatty acids, sodium and potassium are absorbed
- No villi or digestive enzymes- Mucus protects large intestines
from bacterial infections- Bacteria breakdown lactose and
some fiber - Feces formed
Rectum
- Two sphincters control elimination of waste- External sphincter is voluntarily controlled
Accessory organsNot part of GI tract but part of
digestive systema) Liver produces bileb) Gallbladder stores bilec) Pancreas provides enzymes and
hormones:
Extra info: Pancreatic juice containing bicarbonate that neutralizes the acid from the stomach protecting the small intestines as chyme enters
Urinary systemTwo Kidneys remove wastes from the
bodyKidneys help maintain acid-base
balance of the bloodKidneys convert Vit D to an active
hormoneKidneys produce glucose from amino
acids during fastingExcess water-soluble nutrients and
minerals are filteredUrea travels from kidneys to bladder
by ureterBladder empties through urethra
Storage capabilities
- Adipose cells store fat- Muscle and liver store carbohydrates as glycogen- Blood contains a small reserve of amino acids
and glucose- Many vitamins and minerals are stored in the
liver- Calcium is taken from bones if needed- Protein can be taken from muscles if needed
• http://www.youtube.com/watch?v=pGENxQQvRZA&feature=related
• http://www.youtube.com/watch?v=1vFbQjGEhcQ